19-4009; Rev 1; 3/08 KIT ATION EVALU E L B AVAILA 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Features The MAX1021/MAX1043 integrate a multichannel, 10-bit, analog-to-digital converter (ADC) and a 10-bit, digital-toanalog converter (DAC) in a single IC. The devices also include a temperature sensor and configurable generalpurpose I/O ports (GPIOs) with a 25MHz SPITM-/QSPITM-/ MICROWIRETM-compatible serial interface. The ADC is available in an eight input-channel version. The DAC outputs settle within 2.0s, and the ADC has a 225ksps conversion rate. All devices include an internal reference (2.5V) to provide a well-regulated, low-noise reference for both the ADC and DAC. Programmable reference modes for the ADC and DAC allow the use of an internal reference, an external reference, or a combination of both. Features such as an internal 1C accurate temperature sensor, FIFO, scan modes, programmable internal or external clock modes, data averaging, and AutoShutdownTM allow users to minimize both power consumption and processor requirements. The low glitch energy (4nV*s) and low digital feedthrough (0.5nV*s) of the integrated DACs make these devices ideal for digital control of fast-response closed-loop systems. The devices are guaranteed to operate with a supply voltage from +2.7V to +5.25V. They consume 2.5mA at 225ksps throughput, only 22A at 1ksps throughput, and under 0.2A in the shutdown mode. The MAX1021/ MAX1043 offer four GPIOs that can be configured as inputs or outputs. The MAX1021/MAX1043 are available in 36-pin thin QFN packages. These devices are specified over the -40C to +85C temperature range. 10-Bit, 225ksps ADC Analog Multiplexer with True-Differential Track/Hold (T/H) Eight Single-Ended Channels or Four Differential Channels (Unipolar or Bipolar) Excellent Accuracy: 0.5 LSB INL, 0.5 LSB DNL, No Missing Codes Over Temperature 10-Bit, Octal, 2s Settling DAC (MAX1021) Ultra-Low-Glitch Energy (4nV*s) Power-Up Options from Zero Scale or Full Scale Excellent Accuracy: 0.5 LSB INL Internal Reference or External Single-Ended/ Differential Reference Internal Reference Voltage (2.5V) Internal 1C Accurate Temperature Sensor On-Chip FIFO Capable of Storing 16 ADC Conversion Results and One Temperature Result On-Chip Channel-Scan Mode and Internal Data-Averaging Features Analog Single-Supply Operation +2.7V to +5.25V Digital Supply: +2.7V to AVDD 25MHz, SPI/QSPI/MICROWIRE Serial Interface AutoShutdown Between Conversions Low-Power ADC 2.5mA at 225ksps 22A at 1ksps 0.2A at Shutdown Low-Power DAC: 1.5mA Evaluation Kit Available (Order MAX1258EVKIT) Applications Closed-Loop Controls for Optical Components and Base Stations System Supervision and Control Data-Acquisition Systems SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp. AutoShutdown is a trademark of Maxim Integrated Products, Inc. Pin Configurations appear at end of data sheet. Ordering Information/Selector Guide PART PIN-PACKAGE REF ANALOG SUPPLY RESOLUTION ADC VOLTAGE (V) VOLTAGE (V) BITS** CHANNELS DAC CHANNELS GPIOs MAX1021BETX 36 Thin QFN-EP* 2.5 2.7 to 5.25 10 8 8 4 MAX1043BETX 36 Thin QFN-EP* 2.5 2.7 to 5.25 10 8 4 4 Note: All devices are specified over the -40C to +85C operating temperature range. *EP = Exposed pad. **Number of resolution bits refers to both DAC and ADC. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX1021/MAX1043 General Description MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports ABSOLUTE MAXIMUM RATINGS Maximum Current into OUT_.............................................100mA Continuous Power Dissipation (TA = +70C) 36-Pin Thin QFN (6mm x 6mm) (derate 26.3mW/C above +70C) ..........................2105.3mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-60C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C AVDD to AGND .........................................................-0.3V to +6V DGND to AGND.....................................................-0.3V to +0.3V DVDD to AVDD .......................................................-3.0V to +0.3V Digital Inputs to DGND.............................................-0.3V to +6V Digital Outputs to DGND .........................-0.3V to (DVDD + 0.3V) Analog Inputs, Analog Outputs and REF_ to AGND...............................................-0.3V to (AVDD + 0.3V) Maximum Current into Any Pin (except AGND, DGND, AVDD, DVDD, and OUT_) ...........................................................50mA Note: If the package power dissipation is not exceeded, one output at a time can be shorted to AVDD, DVDD, AGND, or DGND indefinitely. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (AVDD = DVDD = 2.7V to 5.25V, external reference VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), TA = -40C to +85C, unless otherwise noted. Typical values are at AVDD = DVDD = 3V, TA = +25C. Outputs are unloaded, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ADC DC ACCURACY (Note 1) Resolution 10 Bits Integral Nonlinearity INL 0.5 1.0 LSB Differential Nonlinearity DNL 0.5 1 LSB Offset Error Gain Error (Note 2) 0.25 2.0 LSB 0.025 2.0 LSB Gain Temperature Coefficient 1.4 ppm/C Channel-to-Channel Offset 0.1 LSB SINAD 61 dB Total Harmonic Distortion (Up to the Fifth Harmonic) THD -70 dBc Spurious-Free Dynamic Range SFDR 66 dBc dBc DYNAMIC SPECIFICATIONS (10kHz sine-wave input, VIN = 2.5VP-P, 225ksps, fCLK = 3.6MHz) Signal-to-Noise Plus Distortion Intermodulation Distortion fIN1 = 9.9kHz, fIN2 = 10.2kHz 72 Full-Linear Bandwidth IMD SINAD > 70dB 100 kHz Full-Power Bandwidth -3dB point 1 MHz External reference 0.8 s Internal reference (Note 4) 218 Conversion clock cycles CONVERSION RATE (Note 3) Power-Up Time 2 tPU _______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports (AVDD = DVDD = 2.7V to 5.25V, external reference VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), TA = -40C to +85C, unless otherwise noted. Typical values are at AVDD = DVDD = 3V, TA = +25C. Outputs are unloaded, unless otherwise noted.) PARAMETER SYMBOL Acquisition Time tACQ Conversion Time tCONV External Clock Frequency fCLK CONDITIONS (Note 5) MIN TYP MAX 0.6 Internally clocked s 5.5 s Externally clocked 3.6 Externally clocked conversion (Note 5) 0.1 3.6 40 60 Duty Cycle UNITS MHz % Aperture Delay 30 ns Aperture Jitter < 50 ps ANALOG INPUTS Unipolar Input Voltage Range (Note 6) Bipolar 0 VREF -VREF / 2 +VREF / 2 Input Leakage Current 0.01 Input Capacitance 1 24 V A pF INTERNAL TEMPERATURE SENSOR Measurement Error (Notes 5, 7) TA = +25C 0.7 TA = TMIN to TMAX 1.0 Temperature Resolution 3.0 1/8 C C/LSB INTERNAL REFERENCE REF1 Output Voltage REF1 Voltage Temperature Coefficient (Note 8) 2.482 2.518 30 TCREF REF1 Output Impedance REF1 Short-Circuit Current 2.50 VREF = 2.5V V ppm/C 6.5 k 0.39 mA EXTERNAL REFERENCE REF1 Input Voltage Range VREF1 REF2 Input Voltage Range (Note 4) VREF2 REF1 Input Current (Note 9) IREF1 REF2 Input Current IREF2 REF mode 11 (Note 4) 1 AVDD + 0.05 REF mode 01 1 AVDD + 0.05 REF mode 11 0 1 VREF = 2.5V, fSAMPLE = 225ksps 25 80 Acquisition between conversions 0.01 1 VREF = 2.5V, fSAMPLE = 225ksps 25 80 Acquisition between conversions 0.01 1 V V A A _______________________________________________________________________________________ 3 MAX1021/MAX1043 ELECTRICAL CHARACTERISTICS (continued) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports ELECTRICAL CHARACTERISTICS (continued) (AVDD = DVDD = 2.7V to 5.25V, external reference VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), TA = -40C to +85C, unless otherwise noted. Typical values are at AVDD = DVDD = 3V, TA = +25C. Outputs are unloaded, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.5 1 LSB 0.5 LSB 10 mV DAC DC ACCURACY (Note 10) Resolution 10 Integral Nonlinearity INL Differential Nonlinearity DNL Offset Error VOS Guaranteed monotonic 3 Offset-Error Drift Gain Error Bits ppm of FS/C 10 GE 1.25 Gain Temperature Coefficient 10 LSB ppm of FS/C 8 DAC OUTPUT No load 0.02 AVDD 0.02 0.1 AVDD 0.1 Output Voltage Range V 10k load to either rail DC Output Impedance Resistive Load to AGND 0.5 Capacitive Load (Note 11) RL AVDD = 2.7V, VREF = 2.5V, gain error < 1% 1 nF 2000 From power-down mode, AVDD = 5V 25 From power-down mode, AVDD = 2.7V 21 1k Output Termination Programmed in power-down mode 1 k 100k Output Termination At wake-up or programmed in power-down mode 100 k Wake-Up Time (Note 12) s DYNAMIC PERFORMANCE (Notes 5, 13) Output-Voltage Slew Rate SR Positive and negative Output-Voltage Settling Time tS To 1 LSB, 400 - C00 hex (Note 7) Digital Feedthrough Code 0, all digital inputs from 0 to DVDD Major Code Transition Glitch Impulse Between codes 2047 and 2048 Output Noise (0.1Hz to 50MHz) Output Noise (0.1Hz to 500kHz) DAC-to-DAC Transition Crosstalk 4 3 V/s 2 5 s 0.5 nV*s 4 nV*s From VREF 660 Using internal reference 720 From VREF 260 Using internal reference 320 0.5 _______________________________________________________________________________________ VP-P VP-P nV*s 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports (AVDD = DVDD = 2.7V to 5.25V, external reference VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), TA = -40C to +85C, unless otherwise noted. Typical values are at AVDD = DVDD = 3V, TA = +25C. Outputs are unloaded, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 2.482 2.50 2.518 UNITS INTERNAL REFERENCE REF1 Output Voltage REF1 Temperature Coefficient TCREF REF1 Short-Circuit Current VREF = 2.5V V 30 ppm/C 0.39 mA EXTERNAL REFERENCE INPUT REF1 Input Voltage Range VREF1 REF1 Input Impedance RREF1 REF modes 01, 10, and 11 (Note 4) 0.7 70 100 AVDD V 130 k DIGITAL INTERFACE DIGITAL INPUTS (SCLK, DIN, CS, CNVST, LDAC) Input-Voltage High VIH Input-Voltage Low VIL Input Leakage Current Input Capacitance DVDD = 2.7V to 5.25V 2.4 V DVDD = 3.6V to 5.25V 0.8 DVDD = 2.7V to 3.6V 0.6 IL 0.01 CIN 15 10 V A pF DIGITAL OUTPUT (DOUT) (Note 14) Output-Voltage Low VOL ISINK = 2mA Output-Voltage High VOH ISOURCE = 2mA 0.4 DVDD 0.5 V Tri-State Leakage Current Tri-State Output Capacitance 10 COUT V 15 A pF DIGITAL OUTPUT (EOC) (Note 14) Output-Voltage Low VOL Output-Voltage High VOH ISINK = 2mA ISOURCE = 2mA 0.4 DVDD 0.5 V Tri-State Leakage Current Tri-State Output Capacitance 10 COUT V 15 A pF DIGITAL OUTPUTS (GPIO_) (Note 14) GPIOC_ Output-Voltage Low ISINK = 2mA 0.4 ISINK = 4mA 0.8 GPIOC_ Output-Voltage High ISOURCE = 2mA GPIOA_ Output-Voltage Low ISINK = 15mA GPIOA_ Output-Voltage High ISOURCE = 15mA DVDD 0.5 V 0.8 DVDD 0.8 10 COUT V V Tri-State Leakage Current Tri-State Output Capacitance V 15 A pF _______________________________________________________________________________________ 5 MAX1021/MAX1043 ELECTRICAL CHARACTERISTICS (continued) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports ELECTRICAL CHARACTERISTICS (continued) (AVDD = DVDD = 2.7V to 5.25V, external reference VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), TA = -40C to +85C, unless otherwise noted. Typical values are at AVDD = DVDD = 3V, TA = +25C. Outputs are unloaded, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS AVDD V POWER REQUIREMENTS (Note 15) Digital Positive-Supply Voltage DVDD Digital Positive-Supply Current DIDD Analog Positive-Supply Voltage AVDD 2.7 Idle, all blocks shut down 0.2 Only ADC on, external reference 4 1 2.70 Idle, all blocks shut down A mA 5.25 V A 0.2 2 fSAMPLE = 225ksps 2.8 4.2 fSAMPLE = 100ksps 2.6 Analog Positive-Supply Current AIDD Only ADC on, external reference All DACs on, no load, internal reference 1.5 REF1 Positive-Supply Rejection PSRR AVDD = 2.7V -77 DAC Positive-Supply Rejection PSRD Output AVDD = 2.7V to 5.25V code = FFFhex 0.1 0.5 mV ADC Positive-Supply Rejection PSRA Fullscale input 0.06 0.5 mV AVDD = 2.7V to 5.25V mA 4.0 dB TIMING CHARACTERISTICS (Figures 6-13) SCLK Clock Period tCP 40 ns SCLK Pulse-Width High tCH 40/60 duty cycle 16 ns SCLK Pulse-Width Low tCL 60/40 duty cycle 16 ns GPIO Output Rise/Fall After CS Rise GPIO Input Setup Before CS Fall LDAC Pulse Width tGOD CLOAD = 20pF 100 tGSU 0 tLDACPWL 20 ns ns ns CLOAD = 20pF, SLOW = 0 1.8 12.0 CLOAD = 20pF, SLOW = 1 10 40 CLOAD = 20pF, SLOW = 0 1.8 12.0 CLOAD = 20pF, SLOW = 1 10 40 SCLK Fall to DOUT Transition (Note 16) tDOT SCLK Rise to DOUT Transition (Notes 16, 17) tDOT CS Fall to SCLK Fall Setup Time tCSS 10 SCLK Fall to CS Rise Setup Time tCSH 0 DIN to SCLK Fall Setup Time tDS 10 ns DIN to SCLK Fall Hold Time tDH 0 ns tCSPWH 50 ns CS Pulse-Width High CS Rise to DOUT Disable tDOD CLOAD = 20pF CS Fall to DOUT Enable tDOE CLOAD = 20pF EOC Fall to CS Fall tRDS 6 30 _______________________________________________________________________________________ ns ns 2000 25 1.5 ns 25.0 ns ns ns ns 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports (AVDD = DVDD = 2.7V to 5.25V, external reference VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), TA = -40C to +85C, unless otherwise noted. Typical values are at AVDD = DVDD = 3V, TA = +25C. Outputs are unloaded, unless otherwise noted.) PARAMETER CS or CNVST Rise to EOC Fall--Internally Clocked Conversion Time CNVST Pulse Width SYMBOL tDOV tCSW CONDITIONS MIN TYP MAX CKSEL = 01 (temp sense) or CKSEL = 10 (temp sense), internal reference on 65 CKSEL = 01 (temp sense) or CKSEL = 10 (temp sense), internal reference initially off 140 CKSEL = 01 (voltage conversion) 9 CKSEL = 10 (voltage conversion), internal reference on 9 CKSEL = 10 (voltage conversion), internal reference initially off 80 UNITS s CKSEL = 00, CKSEL = 01 (temp sense) 40 ns CKSEL = 01 (voltage conversion) 1.4 s Note 1: Tested at DVDD = AVDD = 2.7V. Note 2: Offset nulled. Note 3: No bus activity during conversion. Conversion time is defined as the number of conversion clock cycles multiplied by the clock period. Note 4: See Table 5 for reference-mode details. Note 5: Not production tested. Guaranteed by design. Note 6: See the ADC/DAC References section. Note 7: Fast automated test, excludes self-heating effects. Note 8: Specified over the -40C to +85C temperature range. Note 9: REFSEL[1:0] = 00 or when DACs are not powered up. Note 10: DAC linearity, gain, and offset measurements are made between codes 115 and 3981. Note 11: The DAC buffers are guaranteed by design to be stable with a 1nF load. Note 12: Time required by the DAC output to power up and settle within 1 LSB in the external reference mode. Note 13: All DAC dynamic specifications are valid for a load of 100pF and 10k. Note 14: Only one digital output (either DOUT, EOC, or the GPIOs) can be indefinitely shorted to either supply at one time. Note 15: All digital inputs at either DVDD or DGND. DVDD should not exceed AVDD. Note 16: See the Reset Register section and Table 9 for details on programming the SLOW bit. Note 17: Clock mode 11 only. _______________________________________________________________________________________ 7 MAX1021/MAX1043 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) 0.3 0.2 0.1 0 3.0 3.5 4.0 4.5 5.0 0.2 0.1 MAX1040 toc03 0.1 0 -0.1 -0.2 -0.3 -40 5.5 -15 10 35 60 85 0 256 512 1024 768 TEMPERATURE (C) OUTPUT CODE ADC INTEGRAL NONLINEARITY vs. OUTPUT CODE ADC DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE ADC DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE 0 -0.1 -0.2 0.2 0.1 0 -0.1 -0.2 0.3 0 256 512 0 1024 768 0.2 0.1 0 -0.1 -0.2 -0.3 -0.3 -0.3 MAX1040 toc06 MAX1040 toc05 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V DIFFERENTIAL NONLINEARITY (LSB) 0.1 0.3 DIFFERENTIAL NONLINEARITY (LSB) MAX1040 toc04 0.2 256 512 768 0 1024 256 512 1024 768 OUTPUT CODE OUTPUT CODE OUTPUT CODE ADC OFFSET ERROR vs. ANALOG SUPPLY VOLTAGE ADC OFFSET ERROR vs. TEMPERATURE ADC GAIN ERROR vs. ANALOG SUPPLY VOLTAGE 0.3 0.2 0 0 -0.50 -1.0 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 0 -0.25 -0.5 0.1 MAX1021 toc09 0.25 0.5 GAIN ERROR (LSB) OFFSET ERROR (LSB) 0.4 0.50 MAX1021 toc08 1.0 MAX1021 toc07 0.5 2.5 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 0.2 SUPPLY VOLTAGE (V) 0.3 INTEGRAL NONLINEARITY (LSB) 0.3 0.3 0 2.5 8 ADC INTEGRAL NONLINEARITY vs. OUTPUT CODE MAX1021 toc02 0.4 0.4 ANALOG SHUTDOWN CURRENT (A) MAX1021 toc01 ANALOG SHUTDOWN CURRENT (A) 0.5 ANALOG SHUTDOWN CURRENT vs. TEMPERATURE INTEGRAL NONLINEARITY (LSB) ANALOG SHUTDOWN CURRENT vs. ANALOG SUPPLY VOLTAGE OFFSET ERROR (LSB) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports -40 -15 10 35 TEMPERATURE (C) 60 85 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.0 5.5 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports ADC GAIN ERROR vs. TEMPERATURE -0.5 -1.0 -15 10 35 60 20 10 0.5 0 50 100 150 200 250 0 300 50 100 150 200 250 ANALOG SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE ANALOG SUPPLY CURRENT vs. TEMPERATURE DAC INTEGRAL NONLINEARITY vs. OUTPUT CODE 1.94 1.92 2.00 1.98 1.96 1.94 1.92 AVDD = DVDD = 3V 0.3 1.88 3.0 3.5 4.0 4.5 5.0 5.5 0.1 0 -0.1 -0.2 1.90 1.90 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 0.2 -0.3 -40 -15 10 35 60 85 0 256 512 768 SUPPLY VOLTAGE (V) TEMPERATURE (C) OUTPUT CODE DAC INTEGRAL NONLINEARITY vs. OUTPUT CODE DAC DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE DAC DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE 0 -0.1 -0.2 0.05 0 -0.05 256 512 OUTPUT CODE 768 1024 0.05 0 -0.05 -0.10 -0.10 -0.3 0.10 1024 MAX1040 toc18 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V DIFFERENTIAL NONLINEARITY (LSB) 0.1 MAX1040 toc17 0.2 0.10 DIFFERENTIAL NONLINEARITY (LSB) MAX1040 toc16 0.3 300 MAX1040 toc15 AVDD = DVDD = 5V INTEGRAL NONLINEARITY (LSB) 1.96 2.02 MAX1021 toc14 MAX1021 toc13 1.98 0 1.0 SAMPLING RATE (ksps) 2.00 2.5 1.5 0 0 85 MAX1040 toc12 MAX1040 toc11 30 2.0 SAMPLING RATE (ksps) 2.02 SUPPLY CURRENT (mA) 40 2.5 TEMPERATURE (C) 2.04 INTEGRAL NONLINEARITY (LSB) 50 3.0 ANALOG SUPPLY CURRENT (mA) 0 60 ANALOG SUPPLY CURRENT (mA) GAIN ERROR (LSB) 0.5 ADC EXTERNAL REFERENCE INPUT CURRENT (A) MAX1021 toc10 1.0 -40 ANALOG SUPPLY CURRENT vs. SAMPLING RATE ADC EXTERNAL REFERENCE INPUT CURRENT vs. SAMPLING RATE 1023 1026 1029 1032 OUTPUT CODE 1035 1038 1023 1026 1029 1032 1035 1038 OUTPUT CODE _______________________________________________________________________________________ 9 MAX1021/MAX1043 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) 0.2 0.1 MAX1021 toc20 2 1 0 EXTERNAL REFERENCE = 4.096V -1 3 DAC FULL-SCALE ERROR (LSB) 0.3 3 DAC FULL-SCALE ERROR (LSB) MAX1021 toc19 0.4 DAC FULL-SCALE ERROR (LSB) DAC FULL-SCALE ERROR vs. TEMPERATURE DAC FULL-SCALE ERROR vs. TEMPERATURE INTERNAL REFERENCE 2 1 0 EXTERNAL REFERENCE = 2.5V -1 -2 -2 AVDD = DVDD = 3V AVDD = DVDD = 5V 3.0 3.5 4.0 4.5 5.0 5.5 -15 10 35 60 -40 85 35 60 DAC FULL-SCALE ERROR vs. REFERENCE VOLTAGE DAC FULL-SCALE ERROR vs. REFERENCE VOLTAGE DAC FULL-SCALE ERROR vs. LOAD CURRENT 0.25 0 -0.25 -0.50 -1.0 -1.5 -2.0 -2.5 -0.75 1 2 3 4 5 0 -1 -2 -3 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V -4 -3.0 -1.00 0 0.5 1.0 1.5 2.0 2.5 0 3.0 5 10 15 20 25 REFERENCE VOLTAGE (V) REFERENCE VOLTAGE (V) LOAD CURRENT (mA) DAC FULL-SCALE ERROR vs. LOAD CURRENT INTERNAL REFERENCE VOLTAGE vs. TEMPERATURE ADC REFERENCE SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE -2 -3 -4 2.51 2.50 2.49 1.0 1.5 2.0 LOAD CURRENT (mA) 2.5 3.0 MAX1021 toc27 30 25.0 24.9 24.8 24.7 2.48 0.5 25.1 ADC REFERENCE SUPPLY CURRENT (A) -1 MAX1021 toc26 0 2.52 INTERNAL REFERENCE VOLTAGE (V) MAX1040 toc25 1 85 MAX1040 toc24 -0.5 1 DAC FULL-SCALE ERROR (LSB) 0.50 0 MAX1040 toc23 MAX1040 toc22 0.75 0 10 TEMPERATURE (C) AVDD = DVDD = 5V 0 -15 TEMPERATURE (C) 1.00 DAC FULL-SCALE ERROR (LSB) -40 SUPPLY VOLTAGE (V) DAC FULL-SCALE ERROR (LSB) 2.5 10 -3 -3 0 MAX1021 toc21 DAC FULL-SCALE ERROR vs. ANALOG SUPPLY VOLTAGE DAC FULL-SCALE ERROR (LSB) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports -40 -15 10 35 TEMPERATURE (C) 60 85 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) ______________________________________________________________________________________ 5.0 5.5 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports ADC REFERENCE SUPPLY CURRENT vs. TEMPERATURE 40.7 40.6 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V -60 -80 -100 -120 24.8 AVDD = DVDD = 3V -140 60 -160 -40 85 -15 10 35 60 0 85 ADC IMD PLOT ADC CROSSTALK PLOT DAC OUTPUT LOAD REGULATION vs. OUTPUT CURRENT -20 AMPLITUDE (dB) -80 -100 -60 -80 -100 2.06 2.05 2.04 2.03 -120 -140 -140 2.01 -160 -160 2.00 200 150 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 2.07 -120 100 SINKING SOURCING 2.02 DAC OUTPUT = MIDSCALE 0 50 100 150 200 -30 0 30 90 60 ANALOG INPUT FREQUENCY (kHz) ANALOG INPUT FREQUENCY (kHz) OUTPUT CURRENT (mA) DAC OUTPUT LOAD REGULATION vs. OUTPUT CURRENT GPIO OUTPUT VOLTAGE vs. SOURCE CURRENT GPIO OUTPUT VOLTAGE vs. SOURCE CURRENT 1.27 1.26 1.25 1.24 SINKING 1.23 SOURCING 4 GPIOA0, GPIOA1 OUTPUTS 3 2 GPIOC0, GPIOC1 OUTPUTS 1 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V DAC OUTPUT = MIDSCALE 0 -20 0 10 -10 OUTPUT CURRENT (mA) 20 30 GPIOA0, GPIOA1 OUTPUTS 2.5 2.0 GPIOC0, GPIOC1 OUTPUTS 1.5 1.0 0.5 1.22 1.21 3.0 GPIO OUTPUT VOLTAGE (V) GPIO OUTPUT VOLTAGE (V) 1.28 MAX1040 toc35 5 MAX1040 toc34 1.29 200 2.08 DAC OUTPUT VOLTAGE (V) fCLK = 5.24288MHz fIN1 = 10.080kHz fIN2 = 8.0801kHz SNR = 61.11dBc THD = 73.32dBc ENOB = 9.86 BITS SFDR = 86.34dBc MAX1040 toc32 MAX1040 toc31 0 -40 -60 -30 150 ANALOG INPUT FREQUENCY (kHz) -40 50 100 TEMPERATURE (C) fCLK = 5.24288MHz fIN1 = 9.0kHz fIN2 = 11.0kHz AIN = -6dBFS IMD = 78.0dBc 0 50 TEMPERATURE (C) MAX1040 toc33 35 MAX1040 toc36 10 -20 AMPLITUDE (dB) 24.9 24.7 -15 0 DAC OUTPUT VOLTAGE (V) -40 25.0 EXTERNAL REFERENCE = 2.5V 40.5 -40 fSAMPLE = 32.768kHz fANALOG_)N = 10.080kHz fCLK = 5.24288MHz SINAD = 61.21dBc SNR = 61.21dBc THD = 73.32dBc SFDR = 81.25dBc -20 AMPLITUDE (dB) 40.8 0 MAX1021 toc29 40.9 ADC FFT PLOT 25.1 ADC REFERENCE SUPPLY CURRENT (A) MAX1021 toc28 ADC REFERENCE SUPPLY CURRENT (A) 41.0 MAX1040 toc30 ADC REFERENCE SUPPLY CURRENT vs. TEMPERATURE 0 20 40 60 SOURCE CURRENT (mA) 80 100 0 0 20 40 60 80 100 SOURCE CURRENT (mA) ______________________________________________________________________________________ 11 MAX1021/MAX1043 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) GPIO OUTPUT VOLTAGE vs. SINK CURRENT GPIO OUTPUT VOLTAGE vs. SINK CURRENT 600 GPIOA0, GPIOA1 OUTPUTS 300 1200 900 600 GPIOA0, GPIOA1 OUTPUTS 300 0 0 20 40 60 80 100 SINK CURRENT (mA) 0.50 0.25 0 -0.25 -0.50 -1.00 0 10 20 30 40 50 60 SINK CURRENT (mA) -40 -15 10 35 85 DYNAMIC RESPONSE RISE TIME (RLOAD = 10k, CLOAD = 100pF) MAX1040 toc42 MAX1040 toc41 MAX1040 toc40 60 TEMPERATURE (C) DAC-TO-DAC CROSSTALK (RLOAD = 10k, CLOAD = 100pF) DAC-TO-DAC CROSSTALK (RLOAD = 10k, CLOAD = 100pF) VOUTA 1V/div VOUTA 2V/div VOUT 1V/div VOUTB 10mV/div AC-COUPLED VOUTB 10mV/div AC-COUPLED CS 1V/div AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V MAX1043 100s/div 100s/div 1s/div DYNAMIC RESPONSE RISE TIME (RLOAD = 10k, CLOAD = 100pF) DYNAMIC RESPONSE FALL TIME (RLOAD = 10k, CLOAD = 100pF) DYNAMIC RESPONSE FALL TIME (RLOAD = 10k, CLOAD = 100pF) MAX1040 toc43 CS 2V/div VOUT 1V/div VOUT 2V/div CS 1V/div AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 1s/div MAX1040 toc45 MAX1040 toc44 CS 2V/div 12 0.75 -0.75 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 0 1.00 MAX1040 toc39 GPIOC0, GPIOC1 OUTPUTS TEMPERATURE SENSOR ERROR (C) 900 MAX1040 toc38 1200 GPIO OUTPUT VOLTAGE (mV) GPIOC0, GPIOC1 OUTPUTS TEMPERATURE SENSOR ERROR vs. TEMPERATURE 1500 MAX1040 toc37 1500 GPIO OUTPUT VOLTAGE (mV) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports VOUT 2V/div AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 1s/div ______________________________________________________________________________________ 1s/div 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports MAJOR CARRY TRANSITION (RLOAD = 10k, CLOAD = 100pF) DAC DIGITAL FEEDTHROUGH (RLOAD = 10k, CLOAD = 100pF, CS = HIGH, DIN = LOW) MAJOR CARRY TRANSITION (RLOAD = 10k, CLOAD = 100pF) MAX1040 toc46 MAX1040 toc48 MAX1040 toc47 CS 2V/div CS 1V/div VOUT 10mV/div AC-COUPLED SCLK 1V/div VOUT 100mV/div AC-COUPLED VOUT 20mV/div AC-COUPLED AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 1s/div 200ns/div 1s/div DAC DIGITAL FEEDTHROUGH (RLOAD = 10k, CLOAD = 100pF, CS = HIGH, DIN = LOW) NEGATIVE FULL-SCALE SETTLING TIME (RLOAD = 10k, CLOAD = 100pF) MAX1040 toc50 MAX1040 toc49 SCLK 2V/div VOUT 1V/div VOUT 100mV/div AC-COUPLED VLDAC 1V/div AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 200ns/div 1s/div ______________________________________________________________________________________ 13 MAX1021/MAX1043 Typical Operating Characteristics (continued) (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Typical Operating Characteristics (continued) (AVDD = DVDD = 3V, external VREF = 2.5V, fCLK = 3.6MHz (50% duty cycle), fSAMPLE = 225ksps, CLOAD = 50pF, 0.1F capacitor at REF, TA = +25C, unless otherwise noted.) NEGATIVE FULL-SCALE SETTLING TIME (RLOAD = 10k, CLOAD = 100pF) POSITIVE FULL-SCALE SETTLING TIME (RLOAD = 10k, CLOAD = 100pF) POSITIVE FULL-SCALE SETTLING TIME (RLOAD = 10k, CLOAD = 100pF) MAX1040 toc51 MAX1040 toc53 MAX1040 toc52 VLDAC 2V/div VLDAC 2V/div VOUT_ 1V/div VOUT_ 2V/div VOUT_ 2V/div VLDAC 1V/div AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 2s/div AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V 1s/div 1s/div ADC REFERENCE FEEDTHROUGH (RLOAD = 10k, CLOAD = 100pF) ADC REFERENCE FEEDTHROUGH (RLOAD = 10k, CLOAD = 100pF) MAX1040 toc54 MAX1040 toc55 VREF2 1V/div VREF2 2V/div ADC REFERENCE SWITCHING VDAC-OUT 10mV/div AC-COUPLED ADC REFERENCE SWITCHING 200s/div 14 AVDD = DVDD = 5V EXTERNAL REFERENCE = 4.096V VDAC-OUT 2mV/div AC-COUPLED 200s/div ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports PIN MAX1021 MAX1043 1, 2 1, 2 3 3 4 5 NAME FUNCTION GPIOA0, GPIOA1 General-Purpose I/O A0, A1. GPIOA0, GPIOA1 can sink and source 15mA. EOC Active-Low, End-of-Conversion Output. Data is valid after the falling edge of EOC. 4 DVDD Digital Positive-Power Input. Bypass DVDD to DGND with a 0.1F capacitor. 5 DGND Digital Ground. Connect DGND to AGND. 6 6 DOUT Serial-Data Output. Data is clocked out on the falling edge of the SCLK clock in modes 00, 01, and 10. Data is clocked out on the rising edge of the SCLK clock in mode 11. It is high impedance when CS is high. 7 7 SCLK Serial-Clock Input. Clocks data in and out of the serial interface. (Duty cycle must be 40% to 60%). See Table 5 for details on programming the clock mode. 8 8 DIN Serial-Data Input. DIN data is latched into the serial interface on the falling edge of SCLK. -- 9-12 OUT0-OUT3 DAC Outputs 9-12, 16-19 -- OUT0-OUT7 DAC Outputs 13 13 AVDD Positive Analog Power Input. Bypass AVDD to AGND with a 0.1F capacitor. Analog Ground 14 14 AGND 15, 23, 32, 33 15, 23, 32, 33 N.C. 20 20 LDAC 21 21 CS 22 22 RES_SEL 24, 25 24, 25 No Connection. Not internally connected. Active-Low, Load DAC. LDAC is an asynchronous active-low input that updates the DAC outputs. Drive LDAC low to make the DAC registers transparent. Active-Low, Chip-Select Input. When CS is low, the serial interface is enabled. When CS is high, DOUT is high impedance. Reset Select. Select DAC wake-up mode. Set RES_SEL low to wake up the DAC outputs with a 100k resistor to GND or set RES_SEL high to wake up the DAC outputs with a 100k resistor to VREF. The default is the external VREF. GPIOC0, GPIOC1 General-Purpose I/O C0, C1. GPIOC0, GPIOC1 can sink 4mA and source 2mA. Reference 1 Input. Reference voltage; leave unconnected to use the internal reference (2.5V). REF1 is the positive reference in ADC differential mode. Bypass REF1 to AGND with a 0.1F capacitor in external reference mode only. See the ADC/DAC References section. 26 26 REF1 27-31, 34 27-31, 34 AIN0-AIN5 Analog Inputs Reference 2 Input/Analog Input Channel 6. See Table 5 for details on programming the setup register. 35 35 REF2/AIN6 36 36 CNVST/AIN7 -- 16-19 D.C. -- -- EP Active-Low, Conversion-Start Input/Analog Input 7. See Table 5 for details on programming the setup register. Do Not Connect. Do not connect to this pin. Exposed Pad. Must be externally connected to AGND. Do not use as a ground connect. ______________________________________________________________________________________ 15 MAX1021/MAX1043 Pin Description MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Detailed Description The MAX1021/MAX1043 integrate a multichannel 10-bit ADC and a 10-bit DAC in a single IC. These devices also include a temperature sensor and configurable GPIOs with a 25MHz SPI-/QSPI-/MICROWIRE-compatible serial interface. The ADC is available in an 8 inputchannel version. The DAC outputs settle within 2.0s, and the ADC has a 225ksps conversion rate. These devices include an internal reference (2.5V) providing a well-regulated, low-noise reference for both the ADC and DAC. Programmable reference modes for the ADC and DAC allow the use of an internal reference, an external reference, or a combination of both. Features such as an internal 1C accurate temperature sensor, FIFO, scan modes, programmable internal or external clock modes, data averaging, and AutoShutdown allow users to minimize both power consumption and processor requirements. The low glitch energy (4nV*s) and low digital feedthrough (0.5nV * s) of the integrated DACs make these devices ideal for digital control of fast-response closed-loop systems. The devices are guaranteed to operate with a supply voltage from +2.7V to +5.25V. They consume 2.5mA at 225ksps throughput, only 0.22A at 1ksps throughput, and under 0.2A in shutdown mode. The MAX1021/ MAX1043 offer four GPIOs that can be configured as inputs or outputs. Figure 1 shows the MAX1021 functional diagram. The MAX1021/MAX1043 only include the GPIO A0, A1, GPIO C0, C1 blocks. The output-conditioning circuitry takes the internal parallel data bus and converts it to a serial data format at DOUT, with the appropriate wake-up timing. The arithmetic logic unit (ALU) performs the averaging function. SPI-Compatible Serial Interface The MAX1021/MAX1043 feature a serial interface that is compatible with SPI and MICROWIRE devices. For SPI, ensure the SPI bus master (typically a microcontroller (C)) runs in master mode so that it generates the serial-clock signal. Select the SCLK frequency of 25MHz or less, and set the clock polarity (CPOL) and phase (CPHA) in the C control registers to the same value. The MAX1021/MAX1043 operate with SCLK idling high or low, and thus operate with CPOL = CPHA = 0 or CPOL = CPHA = 1. Set CS low to latch any input data at DIN on the falling edge of SCLK. Output data at 16 DOUT is updated on the falling edge of SCLK in clock modes 00, 01, and 10. Output data at DOUT is updated on the rising edge of SCLK in clock mode 11. See Figures 6-11. Bipolar true-differential results and temperature-sensor results are available in two's complement format, while all other results are in binary. A high-to-low transition on CS initiates the data-input operation. Serial communications to the ADC always begin with an 8-bit command byte (MSB first) loaded from DIN. The command byte and the subsequent data bytes are clocked from DIN into the serial interface on the falling edge of SCLK. The serial-interface and fastinterface circuitry is common to the ADC, DAC, and GPIO sections. The content of the command byte determines whether the SPI port should expect 8, 16, or 24 bits and whether the data is intended for the ADC, DAC, or GPIOs (if applicable). See Table 1. Driving CS high resets the serial interface. The conversion register controls ADC channel selection, ADC scan mode, and temperature-measurement requests. See Table 4 for information on writing to the conversion register. The setup register controls the clock mode, reference, and unipolar/bipolar ADC configuration. Use a second byte, following the first, to write to the unipolar-mode or bipolar-mode registers. See Table 5 for details of the setup register and see Tables 6, 7, and 8 for setting the unipolar- and bipolarmode registers. Hold CS low between the command byte and the second and third byte. The ADC averaging register is specific to the ADC. See Table 9 to address that register. Table 11 shows the details of the reset register. Begin a write to the DAC by writing 0001XXXX as a command byte. The last 4 bits of this command byte are don't-care bits. Write another 2 bytes (holding CS low) to the DAC interface register following the command byte to select the appropriate DAC and the data to be written to it. See the DAC Serial Interface section and Tables 10, 17, and 18. Write to the GPIOs (if applicable) by issuing a command byte to the appropriate register. Writing to the MAX1021/MAX1043 GPIOs requires 1 additional byte following the command byte. See Tables 12-16 for details on GPIO configuration, writes, and reads. See the GPIO Command section. Command bytes written to the GPIOs on devices without GPIOs are ignored. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports AVDD GPIOC0, GPIOC1 MAX1021/MAX1043 GPIOA0, GPIOA1 DVDD MAX1021 USER-PROGRAMMABLE I/O GPIO CONTROL OSCILLATOR INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT0 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT1 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT2 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT3 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT4 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT5 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT6 INPUT REGISTER DAC REGISTER 10-BIT DAC BUFFER OUTPUT CONDITIONING OUT7 SCLK CS DIN SPI PORT DOUT TEMPERATURE SENSOR ADDRESS EOC LOGIC CONTROL CNVST AIN0 AIN5 REF2/ AIN6 CNVST/ AIN7 REF1 T/H 10-BIT SAR ADC FIFO AND ALU REF2 INTERNAL REFERENCE LDAC AGND DGND RES_SEL Figure 1. MAX1021 Functional Diagram ______________________________________________________________________________________ 17 MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Table 1. Command Byte (MSB First) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 Conversion REGISTER NAME 1 X CHSEL2 CHSEL1 CHSEL0 SCAN1 SCAN0 TEMP Setup 0 1 CKSEL1 CKSEL0 REFSEL1 REFSEL0 DIFFSEL1 DIFFSEL0 ADC Averaging 0 0 1 AVGON NAVG1 NAVG0 NSCAN1 NSCAN0 DAC Select 0 0 0 1 X X X X Reset 0 0 0 0 1 RESET SLOW FBGON GPIO Configure 0 0 0 0 0 0 1 1 GPIO Write 0 0 0 0 0 0 1 0 GPIO Read 0 0 0 0 0 0 0 1 No Operation 0 0 0 0 0 0 0 0 X = Don't care. Power-Up Default State The MAX1021/MAX1043 power up with all blocks in shutdown (including the reference). All registers power up in state 00000000, except for the setup register and the DAC input register. The setup register powers up at 00101000 with CKSEL1 = 1 and REFSEL1 = 1. The DAC input register powers up to 3FFh when RES_SEL is high, and it powers up to 000h when RES_SEL is low. 10-Bit ADC The MAX1021/MAX1043 ADCs use a fully differential successive-approximation register (SAR) conversion technique and on-chip track-and-hold (T/H) circuitry to convert temperature and voltage signals into 10-bit digital results. The analog inputs accept both single-ended and differential input signals. Single-ended signals are converted using a unipolar transfer function, and differential signals are converted using a selectable bipolar or unipolar transfer function. See the ADC Transfer Functions section for more data. ADC Clock Modes When addressing the setup, register bits 5 and 4 of the command byte (CKSEL1 and CKSEL0, respectively) control the ADC clock modes. See Table 5. Choose between four different clock modes for various ways to start a conversion and determine whether the acquisitions are internally or externally timed. Select clock mode 00 to configure CNVST/AIN_ to act as a conversion start and use it to request internally timed conversions, without tying up the serial bus. In clock mode 01, use CNVST to request conversions one channel at a time, thereby controlling the sampling speed without tying up the serial bus. Request and start internally 18 timed conversions through the serial interface by writing to the conversion register in the default clock mode, 10. Use clock mode 11 with SCLK up to 3.6MHz for externally timed acquisitions to achieve sampling rates up to 225ksps. Clock mode 11 disables scanning and averaging. See Figures 6-9 for timing specifications on how to begin a conversion. These devices feature an active-low, end-of-conversion output. EOC goes low when the ADC completes the last requested operation and is waiting for the next command byte. EOC goes high when CS or CNVST go low. EOC is always high in clock mode 11. Single-Ended or Differential Conversions The MAX1021/MAX1043 use a fully differential ADC for all conversions. When a pair of inputs are connected as a differential pair, each input is connected to the ADC. When configured in single-ended mode, the positive input is the single-ended channel and the negative input is referred to AGND. See Figure 2. In differential mode, the T/H samples the difference between two analog inputs, eliminating common-mode DC offsets and noise. IN+ and IN- are selected from the following pairs: AIN0/AIN1, AIN2/AIN3, AIN4/AIN5, AIN6/AIN7. See Tables 5-8 for more details on configuring the inputs. For the inputs that are configurable as CNVST, REF2, and an analog input, only one function can be used at a time. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Analog Input (T/H) The equivalent circuit of Figure 2 shows the ADC input architecture of the MAX1021/MAX1043. In track mode, a positive input capacitor is connected to AIN0-AIN7 in single-ended mode and AIN0, AIN2, AIN4, and AIN6 in differential mode. A negative input capacitor is connected to AGND in single-ended mode or AIN1, AIN3, AIN5, and AIN7 in differential mode. For external T/H timing, use clock mode 01. After the T/H enters hold mode, the difference between the sampled positive and negative input voltages is converted. The input capacitance charging rate determines the time required for the T/H to acquire an input signal. If the input signal's AIN0-AIN7 (SINGLE-ENDED), AIN0, AIN2, AIN4, AIN6 (DIFFERENTIAL) REF1 ACQ DAC AGND CIN+ COMPARATOR HOLD CINAGND (SINGLE-ENDED), AIN1, AIN3, AIN5, AIN7 (DIFFERENTIAL) ACQ HOLD ACQ HOLD source impedance is high, the required acquisition time lengthens. Any source impedance below 300 does not significantly affect the ADC's AC performance. A high-impedance source can be accommodated either by lengthening tACQ (only in clock mode 01) or by placing a 1F capacitor between the positive and negative analog inputs. The combination of the analog-input source impedance and the capacitance at the analog input creates an RC filter that limits the analog input bandwidth. Input Bandwidth The ADC's input-tracking circuitry has a 1MHz small-signal bandwidth, making it possible to digitize high-speed transient events and measure periodic signals with bandwidths exceeding the ADC's sampling rate by using undersampling techniques. Anti-alias prefiltering of the input signals is necessary to avoid high-frequency signals aliasing into the frequency band of interest. Analog Input Protection Internal electrostatic-discharge (ESD) protection diodes clamp all analog inputs to AVDD and AGND, allowing the inputs to swing from (AGND - 0.3V) to (AVDD + 0.3V) without damage. However, for accurate conversions near full scale, the inputs must not exceed AVDD by more than 50mV or be lower than AGND by 50mV. If an analog input voltage exceeds the supplies, limit the input current to 2mA. Internal FIFO The MAX1021/MAX1043 contain a first-in/first-out (FIFO) buffer that holds up to 16 ADC results plus one temperature result. The internal FIFO allows the ADC to process and store multiple internally clocked conversions and a temperature measurement without being serviced by the serial bus. If the FIFO is filled and further conversions are requested without reading from the FIFO, the oldest ADC results are overwritten by the new ADC results. Each result contains 2 bytes, with the MSB preceded by four leading zeros. After each falling edge of CS, the oldest available pair of bytes of data is available at DOUT, MSB first. When the FIFO is empty, DOUT is zero. The first 2 bytes of data read out after a temperature measurement always contain the 10-bit temperature result, preceded by four leading zeros, MSB first. AVDD / 2 Figure 2. Equivalent Input Circuit ______________________________________________________________________________________ 19 MAX1021/MAX1043 Unipolar or Bipolar Conversions Address the unipolar- and bipolar-mode registers through the setup register (bits 1 and 0). See Table 5 for the setup register. See Figures 3 and 4 for the transferfunction graphs. Program a pair of analog inputs for differential operation by writing a one to the appropriate bit of the bipolar- or unipolar-mode register. Unipolar mode sets the differential input range from 0 to VREF1. A negative differential analog input in unipolar mode causes the digital output code to be zero. Selecting bipolar mode sets the differential input range to VREF1 / 2. The digital output code is binary in unipolar mode and two's complement in bipolar mode. In single-ended mode, the MAX1021/MAX1043 always operate in unipolar mode. The analog inputs are internally referenced to AGND with a full-scale input range from 0 to the selected reference voltage. MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports The LSB is followed by 2 sub-bits. If another temperature measurement is performed before the first temperature result is read out, the old measurement is overwritten by the new result. Temperature results are in degrees Celsius (two's complement), at a resolution of 8 LSB per degree. See the Temperature Measurements section for details on converting the digital code to a temperature. 10-Bit DAC In addition to the 10-bit ADC, the MAX1021/MAX1043 also include eight (MAX1021) or four (MAX1043) voltage-output, 10-bit, monotonic DACs with less than 1 LSB integral nonlinearity error and less than 0.5 LSB differential nonlinearity error. Each DAC has a 2s settling time and ultra-low glitch energy (4nV*s). The 10-bit DAC code is unipolar binary with 1 LSB = VREF / 1024. DAC Digital Interface Figure 1 shows the MAX1021 functional diagram. The shift register converts a serial 16-bit word to parallel data for each input register operating with a clock rate up to 25MHz. The SPI-compatible digital interface to the shift register consists of CS, SCLK, DIN, and DOUT. Serial data at DIN is loaded on the falling edge of SCLK. Pull CS low to begin a write sequence. Begin a write to the DAC by writing 0001XXXX as a command byte. The last 4 bits of the DAC select register are don't-care bits. See Table 10. Write another 2 bytes to the DAC interface register following the command byte to select the appropriate DAC and the data to be written to it. See Tables 17 and 18. The double-buffered DACs include an input and a DAC register. The input registers are directly connected to the shift register and hold the result of the most recent write operation. The 10-bit DAC registers hold the current output code for the respective DAC. Data can be transferred from the input registers to the DAC registers by pulling LDAC low or by writing the appropriate DAC command sequence at DIN. See Table 17. The outputs of the DACs are buffered through eight (MAX1021)/ four (MAX1043) rail-to-rail op amps. The MAX1021/MAX1043 DAC output voltage range is based on the internal reference or an external reference. Write to the setup register (see Table 5) to program the reference. If using an external voltage reference, bypass REF1 with a 0.1F capacitor to AGND. The internal reference is 2.5V. When using an external reference on these devices, the voltage range is 0.7V to AVDD. 20 DAC Transfer Function See Table 2 for various analog outputs from the DAC. DAC Power-On Wake-Up Modes The state of the RES_SEL input determines the wake-up state of the DAC outputs. Connect RES_SEL to AVDD or AGND upon power-up to be sure the DAC outputs wake up to a known state. Connect RES_SEL to AGND to wake up all DAC outputs at 000h. While RES_SEL is low, the 100k internal resistor pulls the DAC outputs to AGND and the output buffers are powered down. Connect RES_SEL to AVDD to wake up all DAC outputs at 3FFh. While RES_SEL is high, the 100k pullup resistor pulls the DAC outputs to VREF1 and the output buffers are powered down. DAC Power-Up Modes See Table 18 for a description of the DAC power-up and power-down modes. GPIOs In addition to the internal ADC and DAC, the MAX1021/MAX1043 also provide four GPIO channels, GPIOA0, GPIOA1, GPIOC0, and GPIOC1. Read and write to the GPIOs as detailed in Tables 1 and 12-16. Also, see the GPIO Command section. See Figures 11 and 12 for GPIO timing. Table 2. DAC Output Code Table DAC CONTENTS MSB LSB ANALOG OUTPUT 11 1111 1111 1023 + VREF 1024 10 0000 0001 1023 + VREF 1024 10 0000 0000 512 + VREF + VREF = 1024 2 01 0111 0111 511 + VREF 1024 00 0000 0001 1 + VREF 1024 00 0000 0000 ______________________________________________________________________________________ 0 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Clock Modes Internal Clock The MAX1021/MAX1043 can operate from an internal oscillator. The internal oscillator is active in clock modes 00, 01, and 10. Figures 6, 7, and 8 show how to start an ADC conversion in the three internally timed conversion modes. Read out the data at clock speeds up to 25MHz through the SPI interface. External Clock Set CKSEL1 and CKSEL0 in the setup register to 11 to set up the interface for external clock mode 11. See Table 5. Pulse SCLK at speeds from 0.1MHz to 3.6MHz. Write to SCLK with a 40% to 60% duty cycle. The SCLK frequency controls the conversion timing. See Figure 9 for clock mode 11 timing. See the ADC Conversions in Clock Mode 11 section. ADC/DAC References Address the reference through the setup register, bits 3 and 2. See Table 5. Following a wake-up delay, set REFSEL[1:0] = 00 to program both the ADC and DAC for internal reference use. Set REFSEL[1:0] = 10 to program the ADC for internal reference. Set REFSEL[1:0] = 10 to program the DAC for external reference, REF1. When using REF1 or REF2/AIN_ in external-reference mode, connect a 0.1F capacitor to AGND. Set REFSEL[1:0] = 01 to program the ADC and DAC for external-reference mode. The DAC uses REF1 as its external reference, while the ADC uses REF2 as its external reference. Set REFSEL[1:0] = 11 to program the ADC for external differential-reference mode. REF1 is the positive reference and REF2 is the negative reference in the ADC external differential mode. Table 3. GPIO Maximum Sink/Source Current CURRENT GPIOA0, GPIOA1 (mA) GPIOC0, GPIOC1 (mA) Sink 15 4 Source 15 2 When REFSEL[1:0] = 00 or 10, REF2/AIN_ functions as an analog input channel. When REFSEL[1:0] = 01 or 11, REF2/AIN_ functions as the device's negative reference. Temperature Measurements Issue a command byte setting bit 0 of the conversion register to one to take a temperature measurement. See Table 4. The MAX1021/MAX1043 perform temperature measurements with an internal diode-connected transistor. The diode bias current changes from 68A to 4A to produce a temperature-dependent bias voltage difference. The second conversion result at 4A is subtracted from the first at 68A to calculate a digital value that is proportional to absolute temperature. The output data appearing at DOUT is the digital code above, minus an offset to adjust from Kelvin to Celsius. The reference voltage used for the temperature measurements is always derived from the internal reference source to ensure that 1 LSB corresponds to 1/8th of a degree Celsius. On every scan where a temperature measurement is requested, the 12-bit temperature conversion is carried out first. The first 2 bytes of data read from the FIFO contain the result of the 12-bit temperature measurement. If another temperature measurement is performed before the first temperature result is read out, the old measurement is overwritten by the new result. Temperature results are in degrees Celsius (two's complement). See the Applications Information section for information on how to perform temperature measurements in each clock mode. Register Descriptions The MAX1021/MAX1043 communicate between the internal registers and the external circuitry through the SPI-compatible serial interface. Table 1 details the command byte, the registers, and the bit names. Tables 4-12 show the various functions within the conversion register, setup register, unipolar-mode register, bipolar-mode register, ADC averaging register, DAC select register, reset register, and GPIO command register, respectively. Conversion Register Select active analog input channels, scan modes, and a single temperature measurement per scan by issuing a command byte to the conversion register. Table 4 details channel selection, the four scan modes, and how to request a temperature measurement. Start a scan by writing to the conversion register when in clock mode 10 or 11, or by applying a low pulse to the CNVST pin when in clock mode 00 or 01. See Figures 6 and 7 for timing specifications for starting a scan with CNVST. ______________________________________________________________________________________ 21 MAX1021/MAX1043 Write to the GPIOs by writing a command byte to the GPIO command register. Write a single data byte to the MAX1021/MAX1043 following the command byte. The GPIOs can sink and source current. GPIOA0 and GPIOA1 can sink and source up to 15mA. GPIOC0 and GPIOC1 can sink 4mA and source 2mA. See Table 3. MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports A conversion is not performed if it is requested on a channel or one of the channel pairs that has been configured as CNVST or REF2. For channels configured as differential pairs, the CHSEL0 bit is ignored and the two pins are treated as a single differential channel. Select scan mode 00 or 01 to return one result per single-ended channel and one result per differential pair within the selected scanning range (set by bits 2 and 1, SCAN1 and SCAN0), plus one temperature result if selected. Select scan mode 10 to scan a single input channel numerous times, depending on NSCAN1 and NSCAN0 in the ADC averaging register (Table 9). Select scan mode 11 to return only one result from a single channel. Setup Register Issue a command byte to the setup register to configure the clock, reference, power-down modes, and ADC single-ended/differential modes. Table 5 details the bits in the setup-register command byte. Bits 5 and 4 (CKSEL1 and CKSEL0) control the clock mode, acquisition and sampling, and the conversion start. Bits 3 and 2 (REFSEL1 and REFSEL0) set the device for either internal or external reference. Bits 1 and 0 (DIFFSEL1 and DIFFSEL0) address the ADC unipolar-mode and bipolar-mode registers and configure the analog input channels for differential operation. The ADC reference is always on if any of the following conditions are true: 1)The FBGON bit is set to one in the reset register. 2)At least one DAC output is powered up and REFSEL[1:0] (in the setup register) = 00. 3)At least one DAC is powered down through the 100k to VREF and REFSEL[1:0] = 00. If any of the above conditions exist, the ADC reference is always on, but there is a 188 clock-cycle delay before temperature-sensor measurements begin, if requested. 22 Table 4. Conversion Register* BIT NAME -- BIT FUNCTION 7 (MSB) Set to one to select conversion register. X 6 Don't care. CHSEL2 5 Analog-input channel select. CHSEL1 4 Analog-input channel select. CHSEL0 3 Analog-input channel select. SCAN1 2 Scan-mode select. SCAN0 1 Scan-mode select. TEMP 0 (LSB) Set to one to take a single temperature measurement. The first conversion result of a scan contains temperature information. *See below for bit details. CHSEL2 CHSEL1 CHSEL0 SELECTED CHANNEL (N) 0 0 0 AIN0 0 0 1 AIN1 0 1 0 AIN2 0 1 1 AIN3 1 0 0 AIN4 1 0 1 AIN5 1 1 0 AIN6 1 1 1 AIN7 SCAN MODE (CHANNEL N IS SELECTED BY BITS CHSEL2, CHSEL1, AND CHSEL0) SCAN1 SCAN0 0 0 Scans channels 0 through N. 0 1 Scans channels N through the highest numbered channel. 1 0 Scans channel N repeatedly. The ADC averaging register sets the number of results. 1 1 No scan. Converts channel N once only. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports BIT NAME BIT -- 7 (MSB) Set to zero to select setup register. -- 6 Set to one to select setup register. CKSEL1 5 Clock mode and CNVST configuration; resets to one at power-up. MAX1021/MAX1043 Table 5. Setup Register* FUNCTION CKSEL0 4 Clock mode and CNVST configuration. REFSEL1 3 Reference-mode configuration. REFSEL0 2 Reference-mode configuration. DIFFSEL1 1 Unipolar-/bipolar-mode register configuration for differential mode. DIFFSEL0 0 (LSB) Unipolar-/bipolar-mode register configuration for differential mode. *See below for bit details. Table 5a. Clock Modes (see the Clock Modes section) CKSEL1 CKSEL0 CONVERSION CLOCK ACQUISITION/SAMPLING CNVST CONFIGURATION 0 0 Internal Internally timed. CNVST 0 1 Internal Externally timed by CNVST. CNVST 1 0 Internal Internally timed. AIN7 1 1 External (3.6MHz max) Externally timed by SCLK. AIN7 Table 5b. Clock Modes 00, 01, and 10 REFSEL1 REFSEL0 VOLTAGE REFERENCE OVERRIDE CONDITIONS AIN 0 0 Internal (DAC and ADC) 0 1 1 0 AIN 1 Internal reference required. There is a programmed delay of 244 internal-conversion clock cycles for the internal reference to settle after wake-up. Internal reference not used. Internal reference required. There is a programmed delay of 244 internal-conversion clock cycles for the internal reference to settle after wake-up. AIN Default reference mode. Internal reference turns off after scan is complete. If internal reference is turned off, there is a programmed delay of 218 internalconversion clock cycles. Temperature 1 Internal reference turns off after scan is complete. If internal reference is turned off, there is a programmed delay of 218 internal-conversion clock cycles. Temperature Internal (ADC) and external REF1 (DAC) External differential (ADC), external REF1 (DAC) REF2 CONFIGURATION AIN6 Temperature External singleended (REF1 for DAC and REF2 for ADC) AUTOSHUTDOWN AIN Temperature REF2 AIN6 Internal reference required. There is a programmed delay of 244 internal-conversion clock cycles for the internal reference to settle after wake-up. Internal reference not used. Internal reference required. There is a programmed delay of 244 internal-conversion clock cycles for the internal reference to settle after wake-up. REF2 ______________________________________________________________________________________ 23 MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Table 5c. Clock Mode 11 REFSEL1 REFSEL0 0 0 VOLTAGE REFERENCE OVERRIDE CONDITIONS AIN Internal reference turns off after scan is complete. If internal reference is turned off, there is a programmed delay of 218 external conversion clock cycles. Temperature Internal reference required. There is a programmed delay of 244 external conversion clock cycles for the internal reference. Temperature-sensor output appears at DOUT after 188 further external clock cycles. Internal (DAC and ADC) AIN 0 1 1 0 External singleended (REF1 for DAC and REF2 for ADC) Temperature AIN Default reference mode. Internal reference turns off after scan is complete. If internal reference is turned off, there is a programmed delay of 218 external conversion clock cycles. Temperature Internal reference required. There is a programmed delay of 244 external conversion clock cycles for the internal reference. Temperature-sensor output appears at DOUT after 188 further external clock cycles. 1 AIN6 REF2 AIN6 AIN 1 REF2 CONFIGURATION Internal reference not used. Internal reference required. There is a programmed delay of 244 external conversion clock cycles for the internal reference. Temperature-sensor output appears at DOUT after 188 further external clock cycles. Internal (ADC) and external REF1 (DAC) External differential (ADC), external REF1 (DAC) AUTOSHUTDOWN Temperature Internal reference not used. Internal reference required. There is a programmed delay of 244 external conversion clock cycles for the internal reference. Temperature-sensor output appears at DOUT after 188 further external clock cycles. REF2 Table 5d. Differential Select Modes DIFFSEL1 DIFFSEL0 24 FUNCTION 0 0 No data follows the command setup byte. Unipolar-mode and bipolar-mode registers remain unchanged. 0 1 No data follows the command setup byte. Unipolar-mode and bipolar-mode registers remain unchanged. 1 0 1 byte of data follows the command setup byte and is written to the unipolar-mode register. 1 1 1 byte of data follows the command setup byte and is written to the bipolar-mode register. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports BIT NAME BIT UCH0/1 7 (MSB) Configure AIN0 and AIN1 for unipolar differential conversion. FUNCTION UCH2/3 6 Configure AIN2 and AIN3 for unipolar differential conversion. UCH4/5 5 Configure AIN4 and AIN5 for unipolar differential conversion. UCH6/7 4 Configure AIN6 and AIN7 for unipolar differential conversion. X 3 Don't care. X 2 Don't care. X 1 Don't care. X 0 (LSB) Don't care. Table 7. Bipolar-Mode Register (Addressed Through the Setup Register) BIT NAME BIT FUNCTION BCH0/1 7 (MSB) Set to one to configure AIN0 and AIN1 for bipolar differential conversion. Set the corresponding bits in the unipolar-mode and bipolar-mode registers to zero to configure AIN0 and AIN1 for unipolar single-ended conversion. BCH2/3 6 Set to one to configure AIN2 and AIN3 for bipolar differential conversion. Set the corresponding bits in the unipolar-mode and bipolar-mode registers to zero to configure AIN2 and AIN3 for unipolar single-ended conversion. BCH4/5 5 Set to one to configure AIN4 and AIN5 for bipolar differential conversion (MAX1021/MAX1043). Set the corresponding bits in the unipolar-mode and bipolar-mode registers to zero to configure AIN4 and AIN5 for unipolar single-ended conversion. BCH6/7 4 Set to one to configure AIN6 and AIN7 for bipolar differential conversion (MAX1043). Set the corresponding bits in the unipolar-mode and bipolar-mode registers to zero to configure AIN6 and AIN7 for unipolar single-ended conversion. X 3 Don't care. X 2 Don't care. X 1 Don't care. X 0 (LSB) Don't care. ______________________________________________________________________________________ 25 MAX1021/MAX1043 Table 6. Unipolar-Mode Register (Addressed Through the Setup Register) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Unipolar/Bipolar Registers The final 2 bits (LSBs) of the setup register control the unipolar-/bipolar-mode address registers. Set DIFFSEL[1:0] = 10 to write to the unipolar-mode register. Set bits DIFFSEL[1:0] = 11 to write to the bipolarmode register. In both cases, the setup command byte must be followed by 1 byte of data that is written to the unipolar-mode register or bipolar-mode register. Hold CS low and run 16 SCLK cycles before pulling CS high. Table 8. Unipolar/Bipolar Channel Function UNIPOLARMODE REGISTER BIT BIPOLAR-MODE REGISTER BIT CHANNEL PAIR FUNCTION 0 0 Unipolar single-ended 0 1 Bipolar differential 1 0 Unipolar differential 1 1 Unipolar differential If the last 2 bits of the setup register are 00 or 01, neither the unipolar-mode register nor the bipolar-mode register is written. Any subsequent byte is recognized as a new command byte. See Tables 6, 7, and 8 to program the unipolar- and bipolar-mode registers. Both registers power up at all zeros to set the inputs as eight unipolar single-ended channels. To configure a channel pair as single-ended unipolar, bipolar differential, or unipolar differential, see Table 8. In unipolar mode, AIN+ can exceed AIN- by up to VREF. The output format in unipolar mode is binary. In bipolar mode, either input can exceed the other by up to VREF / 2. The output format in bipolar mode is two's complement (see the ADC Transfer Functions section). ADC Averaging Register Write a command byte to the ADC averaging register to configure the ADC to average up to 32 samples for each requested result, and to independently control the number of results requested for single-channel scans. Table 9. ADC Averaging Register* BIT NAME BIT -- 7 (MSB) Set to zero to select ADC averaging register. FUNCTION -- 6 Set to zero to select ADC averaging register. Set to one to select ADC averaging register. -- 5 AVGON 4 Set to one to turn averaging on. Set to zero to turn averaging off. NAVG1 3 Configures the number of conversions for single-channel scans. NAVG0 2 Configures the number of conversions for single-channel scans. NSCAN1 1 Single-channel scan count. (Scan mode 10 only.) NSCAN0 0 (LSB) *See below for bit details. Single-channel scan count. (Scan mode 10 only.) FUNCTION AVGON NAVG1 0 X X Performs one conversion for each requested result. 1 0 0 Performs four conversions and returns the average for each requested result. 1 0 1 Performs eight conversions and returns the average for each requested result. 1 1 0 Performs 16 conversions and returns the average for each requested result. 1 1 1 Performs 32 conversions and returns the average for each requested result. 26 NAVG0 NSCAN1 NSCAN0 0 0 Scans channel N and returns four results. FUNCTION (APPLIES ONLY IF SCAN MODE 10 IS SELECTED) 0 1 Scans channel N and returns eight results. 1 0 Scans channel N and returns 12 results. 1 1 Scans channel N and returns 16 results. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports DAC Select Register Write a command byte 0001XXXX to the DAC select register (as shown in Table 9) to set up the DAC interface and indicate that another word will follow. The last 4 bits of the DAC select register are don't-care bits. The word that follows the DAC select-register command byte controls the DAC serial interface. See Table 17 and the DAC Serial Interface section. Table 10. DAC Select Register BIT NAME -- BIT FUNCTION 7 (MSB) Set to zero to select DAC select register. Reset Register Write to the reset register (as shown in Table 11) to clear the FIFO or reset all registers (excluding the DAC and GPIO registers) to their default states. When the RESET bit in the reset register is set to 0, the FIFO is cleared. Set the RESET bit to one to return all the device registers to their default power-up state. All registers power up in state 00000000, except for the setup register that powers up in clock mode 10 (CKSEL1 = 1 and REFSEL1 = 1). The DAC and GPIO registers are not reset by writing to the reset register. Set the SLOW bit to one to add a 15ns delay in the DOUT signal path to provide a longer hold time. Writing a one to the SLOW bit also clears the contents of the FIFO. Set the FBGON bit to one to force the bias block and bandgap reference to power up regardless of the state of the DAC and activity of the ADC block. Setting the FBGON bit high also removes the programmed wake-up delay between conversions in clock modes 01 and 11. Setting the FBGON bit high also clears the FIFO. GPIO Command Write a command byte to the GPIO command register to configure, write, or read the GPIOs, as detailed in Table 12. -- 6 Set to zero to select DAC select register. -- 5 Set to zero to select DAC select register. -- 4 Set to one to select DAC select register. X 3 Don't care. X 2 Don't care. BIT NAME BIT FUNCTION X 1 Don't care. -- 7 (MSB) Set to zero to select GPIO register. X 0 Don't care. -- 6 Set to zero to select GPIO register. -- 5 Set to zero to select GPIO register. -- 4 Set to zero to select GPIO register. -- 3 Set to zero to select GPIO register. -- 2 Set to zero to select GPIO register. GPIOSEL1 1 GPIO configuration bit. GPIOSEL2 0 (LSB) GPIOSEL1 GPIOSEL2 1 1 GPIO configuration; written data is entered in the GPIO configuration register. 1 0 GPIO write; written data is entered in the GPIO write register. 0 1 GPIO read; the next 8 SCLK cycles transfer the state of all GPIO drivers into DOUT. Table 12. GPIO Command Register Table 11. Reset Register BIT NAME -- BIT FUNCTION 7 (MSB) Set to zero to select ADC reset register. -- 6 Set to zero to select ADC reset register. -- 5 Set to zero to select ADC reset register. -- 4 Set to zero to select ADC reset register. -- 3 Set to one to select ADC reset register. RESET 2 Set to zero to clear the FIFO only. Set to one to set the device in its power-on condition. SLOW 1 Set to one to turn on slow mode. FBGON 0 (LSB) Set to one to force internal bias block and bandgap reference to be always powered up. GPIO write bit. FUNCTION ______________________________________________________________________________________ 27 MAX1021/MAX1043 Table 9 details the four scan modes available in the ADC conversion register. All four scan modes allow averaging as long as the AVGON bit, bit 4 in the averaging register, is set to 1. Select scan mode 10 to scan the same channel multiple times. Clock mode 11 disables averaging. For example, if AVGON = 1, NAVG[1:0] = 00, NSCAN[1:0] = 11 and SCAN[1:0] = 10, 16 results are written to the FIFO, with each result being the average of four conversions of channel N. MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports DAC Serial Interface Write a command byte 0001XXXX to the DAC select register to indicate the word to follow is written to the DAC serial interface, as detailed in Tables 1, 10, 17, and 18. Write the next 16 bits to the DAC interface register, as shown in Tables 17 and 18. Following the high-to-low transition of CS, the data is shifted synchronously and latched into the input register on each falling edge of SCLK. Each word is 16 bits. The first 4 bits are the control bits, followed by 10 data bits (MSB first), followed by 2 sub-bits. See Figures 9-12 for DAC timing specifications. If CS goes high prior to completing 16 SCLK cycles, the command is discarded. To initiate a new transfer, drive CS low again. For example, writing the DAC serial interface word 1111 0000 and 00110100 disconnects DAC outputs 2 and 3 and forces them to a high-impedance state. DAC outputs 0 and 1 remain in their previous state. Write the command byte 00000011 to configure the GPIOs. The eight SCLK cycles following the command byte load data from DIN to the GPIO configuration register in the MAX1021/MAX1043. See Tables 13 and 14. The register bits are updated after the last CS rising edge. All GPIOs default to inputs upon power-up. The data in the register controls the function of each GPIO, as shown in Tables 13, 14, and 16. GPIO Write Write the command byte 00000010 to indicate a GPIO write operation. The eight SCLK cycles following the command byte load data from DIN into the GPIO write register in the MAX1021/MAX1043. See Tables 14 and 15. The register bits are updated after the last CS rising edge. GPIO Read Write the command byte 00000001 to indicate a GPIO read operation. The eight SCLK cycles following the command byte transfer the state of the GPIOs to DOUT in the MAX1021/MAX1043. See Table 16. Table 13. MAX1021/MAX1043 GPIO Configuration DATA PIN GPIO COMMAND BYTE DATA BYTE DIN 0 0 0 0 0 0 1 1 GPIOC1 GPIOC0 GPIOA1 GPIOA0 X X X X DOUT 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Table 14. MAX1021/MAX1043 GPIO Write DATA PIN GPIO COMMAND BYTE DATA BYTE DIN 0 0 0 0 0 0 1 0 GPIOC1 GPIOC0 GPIOA1 GPIOA0 X X X X DOUT 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Table 15. GPIO-Mode Control CONFIGURATION BIT WRITE BIT OUTPUT STATE GPIO FUNCTION 1 1 1 Output 1 0 0 Output 0 1 Tri-state Input 0 Pulldown (open drain) 0 0 Table 16. MAX1021/MAX1043 GPIO Read DATA PIN GPIO COMMAND BYTE DATA BYTE DIN 0 0 0 0 0 0 0 1 X X X X X X X X DOUT 0 0 0 0 0 0 0 0 0 0 0 0 GPIOC1 GPIOC0 GPIOA1 GPIOA0 28 ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports 16-BIT SERIAL WORD MSB LSB CONTROL BITS C3 C2 C1 C0 0 0 0 0 DATA BITS D9 D8 X X D7 D6 D5 D4 D3 D2 D1 D0 X X X X X X X X X X X X DESCRIPTION NOP FUNCTION No operation. Reset all internal registers to 000h and leave output buffers in their present state. Preset all internal registers to FFFh and leave output buffers in their present state. 0 0 0 1 0 X X X X X X X X X X X RESET 0 0 0 1 1 X X X X X X X X X X X Pull-High 0 0 1 0 -- -- -- -- -- -- -- -- -- -- X X DAC0 D9-D0 to input register 0, DAC output unchanged. 0 0 1 1 -- -- -- -- -- -- -- -- -- -- X X DAC1 D9-D0 to input register 1, DAC output unchanged. 0 1 0 0 -- -- -- -- -- -- -- -- -- -- X X DAC2 D9-D0 to input register 2, DAC output unchanged. 0 1 0 1 -- -- -- -- -- -- -- -- -- -- X X DAC3 D9-D0 to input register 3, DAC output unchanged. 0 1 1 0 -- -- -- -- -- -- -- -- -- -- X X DAC4 D9-D0 to input register 4, DAC output unchanged (MAX1021). NOP command (MAX1043). 0 1 1 1 -- -- -- -- -- -- -- -- -- -- X X DAC5 D9-D0 to input register 5, DAC output unchanged (MAX1021). NOP command (MAX1043). 1 0 0 0 -- -- -- -- -- -- -- -- -- -- X X DAC6 D9-D0 to input register 6, DAC output unchanged (MAX1021). NOP command (MAX1043). 1 0 0 1 -- -- -- -- -- -- -- -- -- -- X X DAC7 D9-D0 to input register 7, DAC output unchanged (MAX1021). NOP command (MAX1043). 1 0 1 0 -- -- -- -- -- -- -- -- -- -- X X DAC0-3 D9-D0 to input registers 0-3 and DAC register 0-3. DAC outputs updated (write-through). DAC4-7 D9-D0 to input registers 4-7 and DAC register 4-7 (MAX1021). DAC outputs updated (writethrough). NOP command (MAX1043). DAC0-7 D9-D0 to input registers 0-7 and DAC register 0-7 (MAX1021). D11-D0 to input registers 0-3 and DAC registers 0-3 (MAX1043). DAC outputs updated (write-through). 1 1 0 1 1 0 1 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- X X X X ______________________________________________________________________________________ 29 MAX1021/MAX1043 Table 17. DAC Serial-Interface Configuration Table 17. DAC Serial-Interface Configuration (continued) 16-BIT SERIAL WORD MSB LSB CONTROL BITS -- -- -- -- -- DAC0 -- DAC1 0 -- DAC2 1 -- DAC3 1 1 D7 D6 D5 D4 D3 D2 D1 D0 DAC4 1 0 D8 DAC5 1 D9 DAC6 1 DATA BITS DAC7 C3 C2 C1 C0 -- X -- X X X X DESCRIPTION FUNCTION X X X DAC0-7 D9-D0 to input registers 0-7 (MAX1021). D9-D0 to input registers 0-3 (MAX1043). DAC outputs unchanged. DAC0-7 Input registers to DAC registers indicated by ones, DAC outputs updated, equivalent to software LDAC. (No effect on DACs indicated by zeros.) DAC7- DAC4 are only valid on the MAX1021. These bits are don'tcare bits for the MAX1043. Table 18. DAC Power-Up and Power-Down Commands CONTROL BITS 1 1 1 1 1 30 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 DAC0 DAC1 DAC2 DAC3 DAC4 DAC5 DAC6 C3 C2 C1 C0 DATA BITS DAC7 MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports DESCRIPTION FUNCTION D3 D2 D1 D0 -- -- -- -- -- -- -- -- 0 -- -- -- -- -- -- -- -- 0 -- -- -- -- -- -- -- -- 1 -- -- -- -- -- -- -- -- 0 -- -- -- -- -- -- -- -- 1 0 1 0 0 1 1 0 0 0 1 X Power-Up Power up individual DAC buffers indicated by data in DAC0 through DAC3. A one indicates the DAC output is connected and active. A zero does not affect the DAC's present state. X Power down individual DAC buffers indicated by data in DAC0 through DAC3. A one indicates the Power-Down 1 DAC output is disconnected and high impedance. A zero does not affect the DAC's present state. X Power down individual DAC buffers indicated by data in DAC0 through DAC3. A one indicates the Power-Down 2 DAC output is disconnected and pulled to AGND with a 1k resistor. A zero does not affect the DAC's present state. X Power down individual DAC buffers indicated by data in DAC0 through DAC3. A one indicates the Power-Down 3 DAC output is disconnected and pulled to AGND with a 100k resistor. A zero does not affect the DAC's present state. X Power down individual DAC buffers indicated by data in DAC0 through DAC3. A one indicates the Power-Down 4 DAC output is disconnected and pulled to REF1 with a 100k resistor. A zero does not affect the DAC's present state. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports ADC Transfer Functions Figure 3 shows the unipolar transfer function for singleended or differential inputs. Figure 4 shows the bipolar transfer function for differential inputs. Code transitions occur halfway between successive-integer LSB values. Output coding is binary, with 1 LSB = VREF1 / 1024 for unipolar and bipolar operation, and 1 LSB = +0.125C for temperature measurements. Bipolar true-differential results and temperature-sensor results are available in two's complement format, while all others are in binary. See Tables 6, 7, and 8 for details on which setting (unipolar or bipolar) takes precedence. In unipolar mode, AIN+ can exceed AIN- by up to VREF1. In bipolar mode, either input can exceed the other by up to VREF1 / 2. Partial Reads and Partial Writes If the first byte of an entry in the FIFO is partially read (CS is pulled high after fewer than eight SCLK cycles), the remaining bits are lost for that byte. The next byte of data that is read out contains the next 8 bits. If the first byte of an entry in the FIFO is read out fully, but the second byte is read out partially, the rest of that byte is lost. The remaining data in the FIFO is unaffected and can be read out normally after taking CS low again, as long as the 4 leading bits (normally zeros) are ignored. If CS is pulled low before EOC goes low, a conversion may not be completed and the FIFO data may not be correct. Incorrect writes (pulling CS high before completing eight SCLK cycles) are ignored and the register remains unchanged. Applications Information Internally Timed Acquisitions and Conversions Using CNVST ADC Conversions in Clock Mode 00 In clock mode 00, the wake-up, acquisition, conversion, and shutdown sequence is initiated through CNVST and performed automatically using the internal oscillator. Results are added to the internal FIFO to be read out later. See Figure 6 for clock mode 00 timing after a command byte is issued. See Table 5 for details on programming the clock mode in the setup register. Initiate a scan by setting CNVST low for at least 40ns before pulling it high again. The MAX1021/MAX1043 then wake up, scan all requested channels, store the results in the FIFO, and shut down. After the scan is complete, EOC is pulled low and the results are available in the FIFO. Wait until EOC goes low before pulling CS low to communicate with the serial interface. EOC stays low until CS or CNVST is pulled low again. A temperature-conversion result, if requested, precedes all other FIFO results. Temperature results are available in 12-bit format. Do not issue a second CNVST signal before EOC goes low; otherwise, the FIFO can be corrupted. Wait until all conversions are complete before reading the FIFO. SPI communications to the DAC and GPIO registers are permitted during conversion. However, coupled noise may result in degraded ADC signal-to-noise ratio (SNR). Externally Timed Acquisitions and Internally Timed Conversions with CNVST ADC Conversions in Clock Mode 01 In clock mode 01, conversions are requested one at a time using CNVST and performed automatically using the internal oscillator. See Figure 7 for clock mode 01 timing after a command byte is issued. Setting CNVST low begins an acquisition, wakes up the ADC, and places it in track mode. Hold CNVST low for at least 1.4s to complete the acquisition. If reference mode 00 or 10 is selected, an additional 45s is required for the internal reference to power up. If a temperature measurement is being requested, reference power-up and temperature measurement is internally timed. In this case, hold CNVST low for at least 40ns. ______________________________________________________________________________________ 31 MAX1021/MAX1043 Output-Data Format Figures 6-9 illustrate the conversion timing for the MAX1021/MAX1043. All 10-bit conversion results are output in 2-byte format, MSB first, with four leading zeros and the LSB followed by 2 sub-bits. Data appears on DOUT on the falling edges of SCLK. Data is binary for unipolar mode and two's complement for bipolar mode and temperature results. See Figures 3, 4, and 5 for input/output and temperature-transfer functions. Internally Timed Acquisitions and Conversions Using the Serial Interface ADC Conversions in Clock Mode 10 In clock mode 10, the wake-up, acquisition, conversion, and shutdown sequence is initiated by writing a command byte to the conversion register, and is performed automatically using the internal oscillator. This is the default clock mode upon power-up. See Figure 8 for clock mode 10 timing. VREF = VREF+ - VREFVREF VREF 011....111 OFFSET BINARY OUTPUT CODE (LSB) Set CNVST high to begin a conversion. Sampling is completed approximately 500ns after CNVST goes high. After the conversion is complete, the ADC shuts down and pulls EOC low. EOC stays low until CS or CNVST is pulled low again. Wait until EOC goes low before pulling CS or CNVST low. The number of CNVST signals must equal the number of conversions requested by the scan and averaging registers to correctly update the FIFO. Wait until all conversions are complete before reading the FIFO. SPI communications to the DAC and GPIO registers are permitted during conversion. However, coupled noise may result in degraded ADC SNR. If averaging is turned on, multiple CNVST pulses need to be performed before a result is written to the FIFO. Once the proper number of conversions has been performed to generate an averaged FIFO result (as specified to the averaging register), the scan logic automatically switches the analog input multiplexer to the next requested channel. If a temperature measurement is programmed, it is performed after the first rising edge of CNVST following the command byte written to the conversion register. The temperature-conversion result is available on DOUT once EOC has been pulled low. Temperature results are available in 12-bit format. 011....110 011....101 FS = VREF / 2 + VCOM ZS = COM -FS = -VREF / 2 VREF 1 LSB = VREF / 1024 000....001 000....000 (COM) 111....111 VREF 100....011 100....010 100....001 100....000 -FS -1 0 +1 (COM) INPUT VOLTAGE (LSB) +FS - 1 LSB Figure 4. Bipolar Transfer Function--Full Scale (FS) = VREF / 2 OUTPUT CODE FULL-SCALE TRANSITION 111....111 OFFSET BINARY OUTPUT CODE (LSB) MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports 111....110 FS = VREF 111....101 1 LSB = VREF / 1024 011....111 011....110 000....010 000....001 000....000 111....111 000....011 111....110 111....101 000....010 000....001 000....000 0 1 2 3 FS 100....001 100....000 INPUT VOLTAGE (LSB) FS - 3/2 LSB -256 0 TEMPERATURE (C) Figure 3. Unipolar Transfer Function--Full Scale (FS) = VREF 32 Figure 5. Temperature Transfer Function ______________________________________________________________________________________ +255.5 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports MAX1021/MAX1043 CNVST (UP TO 514 INTERNALLY CLOCKED ACQUISITIONS AND CONVERSIONS) CS SCLK DOUT MSB1 LSB1 MSB2 tRDS EOC Figure 6. Clock Mode 00--After writing a command byte, set CNVST low for at least 40ns to begin a conversion. tCSW CNVST (CONVERSION 2) (ACQUISITION 1) (ACQUISITION 2) CS tDOV SCLK (CONVERSION 1) DOUT MSB1 LSB1 MSB2 EOC Figure 7. Clock Mode 01--After writing a command byte, request multiple conversions by setting CNVST low for each conversion. Initiate a scan by writing a command byte to the conversion register. The MAX1021/MAX1043 then power up, scan all requested channels, store the results in the FIFO, and shut down. After the scan is complete, EOC is pulled low and the results are available in the FIFO. If a temperature measurement is requested, the temperature result precedes all other FIFO results. Temperature results are available in 12-bit format. EOC stays low until CS is pulled low again. Wait until all conversions are complete before reading the FIFO. SPI communications to the DAC and GPIO registers are permitted during conversion. However, coupled noise may result in degraded ADC SNR. Externally Clocked Acquisitions and Conversions Using the Serial Interface ADC Conversions in Clock Mode 11 In clock mode 11, acquisitions and conversions are initiated by writing a command byte to the conversion register and are performed one at a time using SCLK as the conversion clock. Scanning, averaging, and the FIFO are disabled, and the conversion result is available at DOUT during the conversion. Output data is updated on the rising edge of SCLK in clock mode 11. See Figure 9 for clock mode 11 timing. Initiate a conversion by writing a command byte to the conversion register followed by 16 SCLK cycles. If CS is pulsed high between the eighth and ninth cycles, the pulse width must be less than 100s. To continuously convert at 16 cycles per conversion, alternate 1 byte of ______________________________________________________________________________________ 33 MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports DIN (CONVERSION BYTE) (UP TO 514 INTERNALLY CLOCKED ACQUISITIONS AND CONVERSIONS) CS SCLK DOUT MSB1 tDOV LSB1 MSB2 EOC Figure 8. Clock Mode 10--The command byte to the conversion register begins the acquisition (CNVST is not required). zeros (NOP byte) between each conversion byte. If 2 NOP bytes follow a conversion byte, the analog cells power down at the end of the second NOP. Set the FBGON bit to one in the reset register to keep the internal bias block powered. If reference mode 00 is requested, or if an external reference is selected, but a temperature measurement is being requested, wait 45s with CS high after writing the conversion byte to extend the acquisition and allow the internal reference to power up. To perform a temperature measurement, write 24 bytes (192 cycles) of zeros after the conversion byte. The temperature result appears on DOUT during the last 2 bytes of the 192 cycles. Temperature results are available in 12-bit format. Conversion-Time Calculations The conversion time for each scan is based on a number of different factors: conversion time per sample, samples per result, results per scan, if a temperature measurement is requested, and if the external reference is in use. Use the following formula to calculate the total conversion time for an internally timed conversion in clock mode 00 and 10 (see the Electrical Characteristics, as applicable): 34 Total conversion time = tCNV x nAVG x nSCAN + tTS + tINT-REF,SU where: tCNV = tDOV (where tDOV is dependent on clock mode and reference mode selected) nAVG = samples per result (amount of averaging) nSCAN = number of times each channel is scanned; set to one unless [SCAN1, SCAN0] = 10 t TS = time required for temperature measurement (53.1s); set to zero if temperature measurement is not requested tINT-REF,SU = tWU (external-reference wake-up); if a conversion using the external reference is requested. In clock mode 01, the total conversion time depends on how long CNVST is held low or high. Conversion time in externally clocked mode (CKSEL1, CKSEL0 = 11) depends on the SCLK period and how long CS is held high between each set of eight SCLK cycles. In clock mode 01, the total conversion time does not include the time required to turn on the internal reference. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports (ACQUISITION1) (CONVERSION1) (ACQUISITION2) CS SCLK DOUT MSB1 LSB1 MSB2 EOC X = DON'T CARE. Figure 9. Clock Mode 11--Externally Timed Acquisition, Sampling, and Conversion Without CNVST DAC/GPIO Timing Figures 10-13 detail the timing diagrams for writing to the DAC and GPIOs. Figure 10 shows the timing specifications for clock modes 00, 01, and 10. Figure 11 shows the timing specifications for clock mode 11. Figure 12 details the timing specifications for the DAC input select register and 2 bytes to follow. Output data is updated on the rising edge of SCLK in clock mode 11. Figure 13 shows the GPIO timing. Figure 14 shows the timing details of a hardware LDAC command DACregister update. For a software-command DAC-register update, tS is valid from the rising edge of CS, which follows the last data bit in the software command word. LDAC Functionality Drive LDAC low to transfer the content of the input registers to the DAC registers. Drive LDAC permanently low to make the DAC register transparent. The DAC output typically settles from zero to full scale within 1 LSB after 2s. See Figure 14. Layout, Grounding, and Bypassing For best performance, use PC boards. Ensure that digital and analog signal lines are separated from each other. Do not run analog and digital signals parallel to one another (especially clock signals) or do not run digital lines underneath the MAX1021/MAX1043 package. High-frequency noise in the AV DD power supply may affect performance. Bypass the AVDD supply with a 0.1F capacitor to AGND, close to the AVDD pin. Bypass the DVDD supply with a 0.1F capacitor to DGND, close to the DVDD pin. Minimize capacitor lead lengths for best supply-noise rejection. If the power supply is very noisy, connect a 10 resistor in series with the supply to improve power-supply filtering. The MAX1021/MAX1043 thin QFN packages contain an exposed pad on the underside of the device. Connect this exposed pad to AGND. Refer to the MAX1258 EV kit for an example of proper layout. Definitions Integral Nonlinearity Integral nonlinearity (INL) is the deviation of the values on an actual transfer function from a straight line. This straight line can be either a best-straight-line fit or a line drawn between the end points of the transfer function, once offset and gain errors have been nullified. INL for the MAX1021/MAX1043 is measured using the endpoint method. Differential Nonlinearity Differential nonlinearity (DNL) is the difference between an actual step width and the ideal value of 1 LSB. A DNL error specification of less than 1 LSB guarantees no missing codes and a monotonic transfer function. Unipolar ADC Offset Error For an ideal converter, the first transition occurs at 0.5 LSB, above zero. Offset error is the amount of deviation between the measured first transition point and the ideal first transition point. ______________________________________________________________________________________ 35 MAX1021/MAX1043 (CONVERSION BYTE) DIN MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports tCL SCLK 1 tDS 2 3 D13 D14 D12 D11 D1 D0 tDOT tDOE D15 D7 DOUT 32 16 8 5 4 tDH D15 DIN tCH D14 D6 D13 D5 tDOD D12 D4 D1 D0 tCSS tCSPWH tCSH CS Figure 10. DAC/GPIO Serial-Interface Timing (Clock Modes 00, 01, and 10) Bipolar ADC Offset Error Aperture Jitter While in bipolar mode, the ADC's ideal midscale transition occurs at AGND -0.5 LSB. Bipolar offset error is the measured deviation from this ideal value. Aperture jitter (tAJ) is the sample-to-sample variation in the time between the samples. ADC Gain Error Aperture delay (t AD ) is the time between the rising edge of the sampling clock and the instant when an actual sample is taken. Gain error is defined as the amount of deviation between the ideal transfer function and the measured transfer function, with the offset error removed and with a full-scale analog input voltage applied to the ADC, resulting in all ones at DOUT. DAC Offset Error DAC offset error is determined by loading a code of all zeros into the DAC and measuring the analog output voltage. DAC Gain Error DAC gain error is defined as the amount of deviation between the ideal transfer function and the measured transfer function, with the offset error removed, when loading a code of all ones into the DAC. 36 Aperture Delay Signal-to-Noise Ratio For a waveform perfectly reconstructed from digital samples, signal-to-noise ratio (SNR) is the ratio of full-scale analog input (RMS value) to the RMS quantization error (residual error). The ideal, theoretical minimum analogto-digital noise is caused by quantization error only and results directly from the ADC's resolution (N bits): SNR = (6.02 x N + 1.76)dB In reality, there are other noise sources besides quantization noise, including thermal noise, reference noise, clock jitter, etc. Therefore, SNR is calculated by taking the ratio of the RMS signal to the RMS noise. RMS noise includes all spectral components to the Nyquist frequency excluding the fundamental, the first five harmonics, and the DC offset. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports MAX1021/MAX1043 tCH tCL SCLK 1 2 3 32 16 8 5 4 tDH tDS D15 DIN D14 D13 D12 D11 D1 D0 tDOE tDOT D15 D7 DOUT D14 D6 tDOD D13 D5 D12 D4 D1 D0 tCSS tCSPWH tCSH CS Figure 11. DAC/GPIO Serial-Interface Timing (Clock Mode 11) SCLK DIN 1 2 BIT 7 (MSB) 8 BIT 6 BIT 0 (LSB) 10 9 BIT 15 BIT 14 24 BIT 1 BIT 0 DOUT THE COMMAND BYTE INITIALIZES THE DAC SELECT REGISTER THE NEXT 16 BITS SELECT THE DAC AND THE DATA WRITTEN TO IT CS Figure 12. DAC-Select Register Byte and DAC Serial-Interface Word ______________________________________________________________________________________ 37 MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports CS tGOD tGSU GPIO INPUT/OUTPUT Figure 13. GPIO Timing tLDACPWL LDAC tS 1 LSB OUT_ Figure 14. LDAC Functionality Signal-to-Noise Plus Distortion Signal-to-noise plus distortion (SINAD) is the ratio of the fundamental input frequency's RMS amplitude to the RMS equivalent of all other ADC output signals: SINAD(dB) = 20 x log (SignalRMS / NoiseRMS) Effective Number of Bits Effective number of bits (ENOB) indicates the global accuracy of an ADC at a specific input frequency and sampling rate. An ideal ADC's error consists of quantization noise only. With an input range equal to the fullscale range of the ADC, calculate the ENOB as follows: ENOB = (SINAD - 1.76) / 6.02 Total Harmonic Distortion Total harmonic distortion (THD) is the ratio of the RMS sum of the first five harmonics of the input signal to the fundamental itself. This is expressed as: THD = 20 x log 38 (V22 + V32 + V42 + V52 + V62) / V1 where V1 is the fundamental amplitude, and V2 through V6 are the amplitudes of the first five harmonics. Spurious-Free Dynamic Range Spurious-free dynamic range (SFDR) is the ratio of RMS amplitude of the fundamental (maximum signal component) to the RMS value of the next largest distortion component. ADC Channel-to-Channel Crosstalk Bias the ON channel to midscale. Apply a full-scale sine wave test tone to all OFF channels. Perform an FFT on the ON channel. ADC channel-to-channel crosstalk is expressed in dB as the amplitude of the FFT spur at the frequency associated with the OFF channel test tone. Intermodulation Distortion (IMD) IMD is the total power of the intermodulation products relative to the total input power when two tones, f1 and f2, are present at the inputs. The intermodulation products are (f1 f2), (2 x f1), (2 x f2), (2 x f1 f2), (2 x f2 f1). The individual input tone levels are at -7dBFS. ______________________________________________________________________________________ 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports DAC Digital Feedthrough DAC digital feedthrough is the amount of noise that appears on the DAC output when the DAC digital control lines are toggled. Full-Power Bandwidth A large -0.5dBFS analog input signal is applied to an ADC, and the input frequency is swept up to the point where the amplitude of the digitized conversion result has decreased by -3dB. This point is defined as fullpower input bandwidth frequency. ADC Power-Supply Rejection ADC power-supply rejection (PSR) is defined as the shift in offset error when the power supply is moved from the minimum operating voltage to the maximum operating voltage. DAC Power-Supply Rejection DAC PSR is the amount of change in the converter's value at full-scale as the power-supply voltage changes from its nominal value. PSR assumes the converter's linearity is unaffected by changes in the powersupply voltage. 28 29 30 31 32 EOC DVDD 3 DGND DOUT 5 SCLK DIN OUT0 7 21 8 20 9 19 OUT7 27 2 26 25 24 23 AIN1 AIN2 AIN3 AIN4 N.C. N.C. 24 GPIOC0 DGND 5 23 N.C. MAX1043 DOUT 6 22 RES_SEL SCLK 7 21 CS DIN 8 20 LDAC OUT0 9 D.C. D.C. D.C. N.C. AGND AVDD OUT1 THIN QFN (6mm x 6mm x 0.8mm) Package Information Chip Information TRANSISTOR COUNT: 58,141 PROCESS: BiCMOS OUT3 18 OUT6 THIN QFN OUT2 17 10 11 12 13 14 15 16 17 18 OUT5 19 D.C. 16 15 25 GPIOC1 DVDD 4 11 14 26 REF1 EOC 3 10 12 27 AIN0 GPIOA1 2 OUT2 OUT3 AVDD AGND N.C. OUT4 22 GPIOA0 1 OUT1 13 MAX1021 6 AIN5 36 35 34 33 32 31 30 29 28 1 4 REF2/AIN6 N.C. N.C. AIN4 AIN3 AIN2 AIN1 33 TOP VIEW AIN0 REF1 GPIOC1 GPIOC0 N.C. RES_SEL CS LDAC GPIOA0 GPIOA1 CNVST/AIN7 REF2/AIN6 AIN5 34 CNVST/AIN7 35 TOP VIEW 36 Pin Configurations For the latest package outline information, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 36 TQFN T3666-3 21-0141 ______________________________________________________________________________________ 39 MAX1021/MAX1043 Small-Signal Bandwidth A small -20dBFS analog input signal is applied to an ADC so the signal's slew rate does not limit the ADC's performance. The input frequency is then swept up to the point where the amplitude of the digitized conversion result has decreased by -3dB. Note that the T/H performance is usually the limiting factor for the smallsignal input bandwidth. MAX1021/MAX1043 10-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO Ports Revision History REVISION NUMBER REVISION DATE 1 3/08 DESCRIPTION Changed timing characteristic specification PAGES CHANGED 7 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 40 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products.